Although glaucoma is a major cause of blindness in the U.S. population, there is no single screening test that has been shown to be adequately sensitive and specific to detect very early glaucomatous optic atrophy on a population wide basis. Preliminary evidence suggests that changes in the pupillary light response may be observed in the early stages of glaucomatous optic nerve damage. Specifically, there may be an increase in latency of optic nerve constriction as an early sign of optic atrophy. In this application we propose to develop a pupillometer based upon a production microcomputer and utilizing commercially available digital imaging hardware. This instrument will be specifically oriented towards measuring latency and amplitude of the pupillary light response and comparing this data to standard values as we determine them. Our aim is to develop an instrument that can be assembled for under $5,000 in hardware costs and operated by minimally skilled technicians. Using this device we plan to study the patient population available to us in order to determine the relationship between changes in pupillary light response and glaucomatous damage as measured by computerized perimetry, computerized ophthalmoscopy and clinical examination. For this pilot study, we will assemble three groups of patients: 1. Those with documented glaucoma on the basis of intraoculr pressure, visual field changes, and optic disc examination. 2. Those considered glaucoma suspects because of suspicious discs, intraocular pressure over 21, or suspicious fields, but not a combination. 3. Those considered normal on the basis of intraocular pressure, disc exam and fields. We will perform pupillometric analysis on each patient in addition to sequential measurements of intraocular pressure, examination of the optic disc by computerized ophthalmoscoy, and Octopus computerized perimetry. These factors will be compared in order to determine the potential sensitivity and specificity of pupillometry in glaucoma screening.